In this post, I will show you how to determine the softening point of bitumen by the ring ball test method.The procedure is same for bitumen, asphalt or coal.As you know, there are so many types of bitumen available for your pavement construction.You should have good knowledge about its softening point, penetration value etc..for making better pavements.
Before I starting do you know what is mean by softening point?According to ASTM, softening point is the temperature at which a substance or material softens beyond some arbitrary softness.
Similarly, the theory of this experiment is very simple, we need only to find the temperature at which the substance attains a particular degree of softening under specified condition of the test.You know that here the substance is bitumen.
My objective in this experiment is to determine the softening point of asphaltic bitumen and fluxed native asphalt, road tar, coal tar pitch and blown type bitumen.This experiment is done by referring to IS: 1205 – 1978.
Apparatus needed for softening point of bitumen experiment(Ring ball test)
- Ring and ball apparatus
- Thermometer – Low Range : -2 to 80oC, Graduation 0.2oC.High Range : 30 to 200oC, Graduation 0.5oC
Preparation of bitumen for this experiment.
- The sample is just sufficient to fill the ring. The excess sample is cut off by a knife.
- The material is heated between 75 and 100oC. Stir it to remove air bubbles and water, and filter it through IS Sieve 30, if necessary.
- The rings are heated and glycerin is applied. The material is filled in it and is cooled it for 30 minutes.
- The excess material is removed with the help of a warmed, sharp knife.
Procedure for finding the softening point of bitumen(Ring ball test)
A) Materials of softening point below 80oC:
- The apparatus is assembled with the rings, thermometer and ball guides in position.
- The beaker is filled with boiled distilled water at a temperature 5.0 ± 0.5oC per minute.
- With the help of a stirrer, stir the liquid and heat is applied to the beaker at a temperature of 5.0 ± 0.5oC per minute.
- The heat is applied until the material softens and the ball is allowed to pass through the ring.
- The temperature is recorded at which the ball touches the bottom, which is nothing but the softening point of bitumen or that material.
B) Materials of softening point above 80oC:
- The procedure using ring ball apparatus for above 800-degrees Celcius is the same as described above. The only difference is that instead of water, glycerine is used and the starting temperature of the test is 35oC.